Faculty at Case Western Reserve University and its Comprehensive Cancer Center with key collaborators at the University of Kentucky, and University of Minnesota propose to develop a novel stem cell graft engineering approach that will address the known limitations of unrelated donor umbilical cord blood (UCB) transplantation, namely, delayed hematopoietic and immune recovery. Current gaps in knowledge in UCB 2 unit allogeneic transplantation are 1.) that graft parameters including HLA match and cell dose do not predict which of 2 units infused ultimately engrafts and 2.) whether graft vs. graft immune reactivity may underlie improved rates and kinetics of myeloid engraftment in the 2 unit setting. The hypothesis to be tested in this study which will be conducted under FDA IND is whether UCB graft hematopoietic stem cell (HSC) and T-cell homing and engraftment is enhanced by manipulating the chemokine SDF-1/CXCR-4 axis. We posit that responsiveness of HSC to SDF-1 gradient is a pivotal factor that besides a number of transplanted HSC determine success of stem cell homing and engraftment. Our laboratory data setting the basis for our current FDA IND show that responsiveness of UCB HSC to SDF-1 gradient is enhanced/primed by C3 cleavage fragment short-term (30 minute) co-culture. This hypothesis will be tested under 3 specific aims: Specific Aim 1: Responsiveness of UCB cells to SDF-1 gradient as a new parameter to evaluate quality of the graft. We postulate that functional responsiveness of HSC to SDF-1 is a pivotal parameter to evaluate quality of the stem cell graft. In parallel in vitro chemotactic assays we will study whether responsiveness of UCB CD34 HSC to an SDF-1 gradient correlates with their engraftment efficiency in humans. Specific Aim 2. Priming of UCB before transplantation as a new strategy to enhance engraftment of HSC. We will evaluate how priming strategy of UCB before transplantation improves engraftment of UCB CD34 HSC. We will focus on molecular events that explain this priming phenomenon. Specific Aim 3: Impact of C3a fragment priming on UCB graft CD4 T-cell activation. We will evaluate how C3a priming of UCB grafts before transplantation may elicit CD4 T-cell activation and determine whether this improves engraftment of UCB HSC. PUBLIC HEALTH RELEVANCE: Case Western Reserve University with its collaborators at University of Louisville, and University of Minnesota with strong multidisciplinary faculty are conducting studies focused on testing the concept that infusion of C3a primed umbilical cord blood hematopoietic stem cells will enhance their homing and engraftment in the recipient. We have observed in laboratory studies that stem cells treated with C3a demonstrate improved homing and engraftment. If successful, this treatment approach may improve stem cell therapy safety and efficacy. The concept underlying this proposed treatment is innovative. Although prior studies incorporating double cord blood unit cellular strategies have been attempted and are successful to overcome the cell dose barrier to transplant in adult patients, this proposal is unique in the incorporation of C3a priming of hematopoietic stem cells to enhance their homing and engraftment.